I. Field
The present invention relates to data communication. More particularly, the present invention relates to a novel and improved method and apparatus for transmitting messages in a wireless communication system.
II. Description of the Related Art
Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), or some other modulation techniques. A CDMA system provides certain advantages over other types of system, including increased system capacity.
A CDMA system may be designed to support one or more CDMA standards such as (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the “TIA/EIA-98-C Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station” (the IS-98 standard), (3) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (4) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems,” the “C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” and the “C.S0024 cdma2000 High Rate Packet Data Air Interface Specification” (the cdma2000 standard), and (5) some other standards. These standards are incorporated herein by reference. A system that implements the High Rate Packet Data specification of the cdma2000 standard is referred to herein as a high data rate (HDR) system. Proposed wireless systems also provide a combination of HDR and low data rate services (such as voice and fax services) using a single air interface.
In a wireless communication system, the transmit power required for a transmission is dependent on the propagation (or path) loss between a transmitting entity (e.g., an access terminal) and a receiving entity (e.g., an access point). As an access terminal moves further away from the access point, the path loss typically increases. Consequently, more transmit power is required so that the transmission can be received at the required signal quality for the desired level of performance (e.g., one percent frame error rate). However, the higher transmit power for this transmission causes more interference to the transmissions from other access terminals. The higher transmit power also causes faster depletion of battery power on mobile wireless devices. There is, therefore, a need in the art for a way to provide HDR services that minimizes interference and depletion of battery power.